linux-kernel - [PATCH AUTOSEL 6.8 65/68] netdev: let netlink core handle -EMSGSIZE errors

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Date: Fri, 29 Mar 2024 08:26:01 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Ido Schimmel <idosch@...dia.com>,
	"David S . Miller" <davem@...emloft.net>,
	Sasha Levin <sashal@...nel.org>,
	pabeni@...hat.com,
	amritha.nambiar@...el.com,
	sridhar.samudrala@...el.com,
	sdf@...gle.com,
	ast@...nel.org,
	maciej.fijalkowski@...el.com,
	hawk@...nel.org,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 6.8 65/68] netdev: let netlink core handle -EMSGSIZE errors

From: Jakub Kicinski <kuba@...nel.org>

[ Upstream commit 0b11b1c5c320555483e8a94c44549db24c289987 ]

Previous change added -EMSGSIZE handling to af_netlink, we don't
have to hide these errors any longer.

Theoretically the error handling changes from:
 if (err == -EMSGSIZE)
to
 if (err == -EMSGSIZE && skb->len)

everywhere, but in practice it doesn't matter.
All messages fit into NLMSG_GOODSIZE, so overflow of an empty
skb cannot happen.

Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/core/netdev-genl.c    | 15 +++------------
 net/core/page_pool_user.c |  2 --
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index fd98936da3aec..918b109e0cf40 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -152,10 +152,7 @@ int netdev_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 	rtnl_unlock();
 
-	if (err != -EMSGSIZE)
-		return err;
-
-	return skb->len;
+	return err;
 }
 
 static int
@@ -287,10 +284,7 @@ int netdev_nl_napi_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 	rtnl_unlock();
 
-	if (err != -EMSGSIZE)
-		return err;
-
-	return skb->len;
+	return err;
 }
 
 static int
@@ -463,10 +457,7 @@ int netdev_nl_queue_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 	rtnl_unlock();
 
-	if (err != -EMSGSIZE)
-		return err;
-
-	return skb->len;
+	return err;
 }
 
 static int netdev_genl_netdevice_event(struct notifier_block *nb,
diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
index 278294aca66ab..3a3277ba167b1 100644
--- a/net/core/page_pool_user.c
+++ b/net/core/page_pool_user.c
@@ -103,8 +103,6 @@ netdev_nl_page_pool_get_dump(struct sk_buff *skb, struct netlink_callback *cb,
 	mutex_unlock(&page_pools_lock);
 	rtnl_unlock();
 
-	if (skb->len && err == -EMSGSIZE)
-		return skb->len;
 	return err;
 }
 
-- 
2.43.0